Annual variation in maternal age and calving date generate cohort effects in moose (<Emphasis Type="Italic">Alces alces</Emphasis>) body mass

A general feature of the demography of large ungulates is that many demographic traits are dependent on female body mass at early ages. Thus, identifying the factors affecting body mass variation can give important mechanistic understanding of demographic processes. Here we relate individual variation in autumn and winter body mass of moose calves living at low density on an island in northern Norway to characteristics of their mother, and examine how these relationships are affected by annual variation in population density and climate. Body mass increased with increasing age of their mother, was lower for calves born late in the spring, decreased with litter size and was larger for males than for female calves. No residual effects of variation in density and climate were present after controlling for annual variation in mother age and calving date. The annual variation in adult female age structure and calving date explained a large part (71–75%) of the temporal variation in calf body mass. These results support the hypotheses that (a) body mass of moose calves are affected by qualities associated with mother age (e.g. body condition, calving date); and (b) populations living at low densities are partly buffered against temporal fluctuations in the environment.     

Conception date affects litter type and foetal sex ratio in female moose in Estonia

1.  The Trivers–Willard model of optimal sex ratios predicts that in polygynous species mothers in better condition should produce more male than female offspring. However, empirical support for this hypothesis in mammals and especially ungulates has been equivocal. This may be because the fitness of mothers has been defined in different ways, reflecting morphological, physiological or behavioural measures of condition. In addition, factors other than maternal condition can influence a mother's fitness. Given that recent studies of wild ungulates have demonstrated the importance of the timing of conception and birth on offspring fitness, litters conceived at different stages of the rut might be expected to exhibit differences in types and embryonic sex ratio.
2.  Based on a 6-year survey of the reproductive tracts of female moose harvested in Estonia, we investigated the effect of conception date on the types of litters produced and on the foetal sex ratio.
3.  There was a clear relationship between conception date and litter characteristics. Overall, earlier conceived litters were more likely than those conceived late to contain multiple embryos and a high proportion of males. However, while foetal sex ratio varied nonlinearly with conception date in yearlings and subadults, no relationship was found in adults.
4.  We conclude that female moose adjust foetal sex ratio and litter type/size depending on their age and the date of conception, and that these adjustments are in accordance with the Trivers–Willard hypothesis if females that conceive earlier are in better condition.     

Density-dependent habitat selection and partitioning between two sympatric ungulates

Theory on density-dependent habitat selection predicts that as population density of a species increases, use of higher quality (primary) habitat by individuals declines while use of lower quality (secondary) habitat rises. Habitat partitioning is often considered the primary mechanism for coexistence between similar species, but how this process evolves with changes in population density remains to be empirically tested for free-ranging ungulates. We used resource-selection functions to quantify density effects on landscape-scale habitat selection of two sympatric species of ungulates [moose (Alces alces) and elk (Cervus canadensis manitobensis)] in Riding Mountain National Park, Manitoba, Canada (2000–2011). The density of elk was actively reduced from 1.2 to 0.4 elk km^?2 through increased hunting effort during the period of study, while moose density decreased without additional human influence from 1.6–0.7 moose km^?2. Patterns of habitat selection during winter by both species changed in accordance to expectations from density-dependent habitat-selection theory. At low intraspecific density, moose and elk did not partition habitat, as both species selected strongly for mixed forest (primary habitat providing both food and cover), but did so in different areas segregated across an elevational gradient. As intraspecific density increased, selection for primary habitat by both species decreased, while selection for secondary, lower quality habitat such as agricultural fields (for elk) and built-up areas (for moose) increased. We show that habitat-selection strategies during winter for moose and elk, and subsequent effects on habitat partitioning, depend heavily on the position in state space (density) of both species.     

Range-body mass interactions of a northern ungulate – a test of hypothesis

Summer diet, summer temperature, length of the growth season and animal density appeared to best explain annual and regional differences in calf and yearling body mass in moose from southeastern Norway. In general animals inhabiting steep, alpine landscapes had less body mass than animals using flat, low-altitude habitats. Autumn body mass of calves and yearlings decreased with increasing snow depth during the preceding winter and spring. However, calf body mass was more influenced by the summer range and less by the winter range than was body mass of yearlings. There was no indication that the effect of snow depth on autumn body mass was greater in moose living on poor than on good summer ranges. Body mass decreased with increasing competition for summer forage, while the winter range mainly had an density-independent effect. Habitat quality, expressed as regression lines between calf and yearling body mass and animal density (hunting yield), differed between regions. On ranges of medium and high altitude where birch (Betula spp.) rowan (Sorbus aucuparia) and bilberry (Vaccinium myrtillus) dominated moose summer diet, body mass decreased at a rapid rate with increasing animal density. Body mass decreased at a slower rate at low-altitude ranges and at high-altitude ranges where willow (Salix spp.) and forbs dominated the diet. Body mass of lactating cows decreased with increasing animal density, but animal density did not affect body mass of non-lactating cows. There was no indication that the decrease in autumn body mass with increasing moose density over the last 25 years has caused a decrease in animal condition (ability to survive the winter). The results are discussed in relation to the effect of summer and winter range on population regulation in moose. It is concluded that a density-dependent effect is apparent on the summer range even at low and intermediate population densities. On the winter range, on the other hand, density-dependence is likely to occur only at high levels of population density. Received: 4 February 1997 / Accepted: 1 February 1999     

Seasonal diets of red foxes in a boreal forest with a dense population of moose: the importance of winter scavenging

In Scandinavia, an increased red fox Vulpes vulpes density during the last decades has been suggested to be caused by direct and indirect human influences on food availability. Recently, attention has been focused on the role of increasing scavenging opportunities due to intensified hunting of ungulates and the reestablishment of large carnivores. In our study, we investigated seasonal and annual variations in diet composition of red fox in Varaldskogen, SE Norway, an area with cyclic voles and a high density of moose Alces alces. Analyses of scats revealed significant differences among seasons in the occurrence of ungulates—mainly moose—and ungulates were the dominating food category during winter (44.9 % of all remains). Snow tracking of red fox (71 km) in winter confirmed the importance of ungulate carcasses, i.e. one case of scavenging per 3 km. The proportions of voles were high during all seasons (11.2–28.8 %); in spite of variation in available abundances, no significant seasonal or annual differences were detected. Other food categories with seasonal variation were birds, berries/seeds and amphibians/reptiles, all more common in snow-free seasons. Our study underlines the importance of ungulate remains during periods when the abundance and diversity of alternative food sources is low. Increased and stabilized populations of red foxes—mediated through remains from hunting and wolf kills from high moose populations—might have an important effect on the population dynamics of small game. Hence, we recommend that this relationship be given attention in future studies.     

Dynamics of a harvested moose population in a variable environment

1. Population size, calves per female, female mean age and adult sex ratio of a moose ( Alces alces ) population in Vefsn, northern Norway were reconstructed from 1967 to 1993 using cohort analysis and catch-at-age data from 96% (6752) of all individuals harvested.
2. The dynamics of the population were influenced mainly by density-dependent harvesting, stochastic variation in climate and intrinsic variation in the age-structure of the female segment of the population.
3. A time delay in the assignment of hunting permits in relation to population size increased fluctuations in population size.
4. Selective harvesting of calves and yearlings increased the mean age of adult females in the population, and, because fecundity in moose is strongly age-specific, the number of calves per female concordantly increased. However, after years with high recruitment, the adult mean age decreased as large cohorts entered the adult age-groups. This age-structure effect generated cycles in the rate of recruitment to the population and fluctuations introduced time-lags in the population dynamics.
5. An inverse relationship between recruitment rate and population density, mediated by a density-dependent decrease in female body condition, could potentially have constituted a regulatory mechanism in the dynamics of the population, but this effect was counteracted by a density-dependent increase in the mean age of adult females.
6. Stochastic variation in winter snow depth and summer temperature had delayed effects on recruitment rate and in turn population growth rate, apparently through effects on female body condition before conception.     

Migratory behavior of related moose

In a Swedish moose population containing both migratory and non-migratory individuals, 15 cows, 19 first generation and 2 second generation offspring were radiocollared and monitored during 1980–87 to determine their migratory behavior. The migratory behavior of offspring was evaluated when they were > 1 year old and independent of their dams. All 11 migratory cows produced migratory offspring (10♀, 3♂). Two migratory offspring produced female calves (grandchildren to the originally sampled cows) that were also migratory. Four of the originally sampled cows were non-migratory and they produced six non-migratory offspring (3♀, 3♂). Distances migrated by independent offspring were related to those of their dam. No moose changed its migrant or non-migrant nature during the study. Results indicate that the proportion of migratory moose in the population is determined by the survival and reproductive success of migratory versus non-migratory cows. Migratory and non-migratory moose may be regarded as two distinct phenotypes in this population.     

Habitat quality mediates demographic response to climate in a declining large herbivore

Understanding the interacting role of climate and habitat in shaping wildlife population dynamics can help to reveal synergistic pathways that drive population resilience or decline across variable and changing environments. Moose (Alces alces) is a pan-boreal herbivore experiencing population declines across large portions of North America; however, the species has shown variable response to climate across its distribution. We investigated moose demographic response to climate and evaluated the interacting role of habitat across 36 years and along a biogeographic gradient in Ontario, Canada that has experienced decadal changes to climate and habitat quality. Moose density exhibited a nonlinear trend that initially increased and then decreased over the study timeframe and was negatively affected by regional and local patterns of winter severity and later frost onset. Recruitment exhibited a monotonic decline and was positively affected by spring heat and deciduous forest cover, while also exhibiting density-dependent effects. The negative response of moose density to winter severity was reduced in Wildlife Management Units (WMUs) with higher proportions of dense canopy cover, supporting expectations that this habitat type improves moose winter mobility and predator avoidance. The negative effect of later frost onset was greater in WMUs with more regenerating forest, and both variables are associated with higher exposure to parasites and predators. Further, density-dependent effects on recruitment were suppressed by warmer springs that support vegetation productivity and in WMUs with higher proportions of dense canopy cover that can provide concealment from predators. Our study illustrates the important role habitat conditions can have to mitigate, or exacerbate, climate-change effects for a wide-spread herbivore occupying variable environments by potentially altering pathways relevant to energetic balance, predation, and parasite transmission. In this system, moose occupying sparse or regenerating forests are more susceptible to adverse climatic effects and should be managed accordingly.     

Complex patterns of population genetic structure of moose, Alces alces, after recent spatial expansion in Poland revealed by sex-linked markers

In recent years, human activity directly and indirectly influenced the demography of moose in Poland. The species was close to extinction, and only a few isolated populations survived after the Second World War; then, unprecedented demographic and spatial expansions had occurred, possibly generating a very complex pattern of population genetic structure at the present-day margins of the species range in Poland. Over 370 moose from seven populations were collected from Poland, and partial sequences of the mitochondrial control region (mtDNA-cr; 607 bp) were obtained. In addition, the entire mtDNA cytochrome b gene (1,140 bp) and Y-chromosome markers (1,982 bp in total) were studied in a chosen set of individuals. Twelve mtDNA haplotypes that all belonged to the European moose phylogroup were recorded. They could be divided into two distinct clades: Central Europe and the Ural Mountains. The first clade consists of three distinct groups/branches: Biebrza, Polesie, and Fennoscandia. The Biebrza group has experienced spatial and demographic expansion in the recent past. Average genetic differentiation among moose populations in Poland at mtDNA-cr was great and significant (Φ _ST?=?0.407, p?<?0.001). Using mtDNA-cr data, four separate groups of population were recognized using spatial analysis of molecular variance and principal coordinate analysis, including a relict population in Biebrza National Park, a reintroduced Kampinos National Park population, as well as populations that were descendants of moose that colonized Poland from the east (Lithuania, Belarus, and Ukraine) and the north (former East Prussia). Among all the sequenced Y-chromosome markers, polymorphisms were found in the DBY14 marker in three populations only; four haplotypes were recorded in total. No significant differentiation was detected for this Y-linked marker among moose populations in Poland. Our mtDNA study revealed that a variety of different factors—bottleneck, the presence of relict, autochthonous populations, translocations, limited female dispersal, and the colonization from the east and north—are responsible for the observed complex pattern of population genetic structure after demographic and spatial expansion of moose in Poland.     

Patterns and causes of demographic variation in a harvested moose population: evidence for the effects of climate and density-dependent drivers

1.?Better understanding of the mechanisms affecting demographic variation in ungulate populations is needed to support sustainable management of harvested populations. While studies of moose Alces alces L. populations have previously explored temporal variation in demographic processes, managers responsible for populations that span large heterogeneous landscapes would benefit from an understanding of how demography varies across biogeographical gradients in climate and other population drivers. Evidence of thresholds in population response to manageable and un-manageable drivers could aid resource managers in identifying limits to the magnitude of sustainable change. 2.?Generalized additive models (GAMs) were used to evaluate the relative importance of population density, habitat abundance, summer and winter climatic conditions, primary production, and harvest intensity in explaining spatial variation in moose vital rates in Ontario, Canada. Tree regression was used to test for thresholds in the magnitudes of environmental predictor variables that significantly affected population vital rates. 3.?Moose population growth rate was negatively related to moose density and positively related to the abundance of mixed deciduous habitat abundant in forage. Calf recruitment was negatively related to a later start of the growing season and calf harvest. The ratio of bulls to cows was related to male harvest and hunter access, and thresholds were evident in predictor variables for all vital rate models. 4.?Findings indicate that the contributions of density-dependent and independent factors can vary depending on the scale of population process. The importance of density dependence and habitat supply to low-density ungulate populations was evident, and management strategies for ungulates may be improved by explicitly linking forest management and harvest. Findings emphasize the importance of considering summer climatic influences to ungulate populations, as recruitment in moose was more sensitive to the timing of vegetation green-up than winter severity. The efficacy of management decisions for harvested ungulates may require regional shifts in targets where populations span bioclimatic gradients. The use of GAMs in combination with recursive partitioning was demonstrated to be an informative analytical framework that captured nonlinear relationships common in natural processes and thresholds that are relevant to population management in diverse systems.     

Linking weather conditions and winter tick abundance in moose

Climate change may modify species distribution to higher latitudes, resulting in potential changes of parasite diversity and transmission dynamics in areas where animals might not be locally adapted to these new parasite species. In addition, climate change may increase the frequency and severity of infestations of parasites that are already present in a region, by promoting the development and survival of infectious stages. Over the last decades, the number of moose (Alces americanus) infested by winter ticks (Dermacentor albipictus) has increased in eastern Canada, possibly because milder climatic conditions are increasing winter tick survival. Our main objective was to determine which meteorological variables are more likely to influence winter tick load on moose. We compiled several weather variables that may limit winter tick survival and explored which weather variables, or their interactions, influenced the winter tick load of 4,100 hunted moose from 2013 to 2019 in Québec, Canada along a latitudinal gradient. Winter tick load in fall decreased with the maximum number of consecutive days in spring with average daily temperatures below −15°C and with the number of consecutive days in summer with a relative humidity <80% when snowmelt in spring was earlier. These results suggest that cold temperatures and prolonged periods of low humidity, amplified by early snowmelt, limit the survival of adult female ticks and eggs, thus limiting their subsequent load on moose during the following fall. With climate change, precipitation increases and warm temperatures occur earlier in spring and are more frequent in summer. Our results suggest that climate change may have a positive long-term influence on winter tick abundance in the environment and thereby increase winter tick load on moose, which could lead to a significant decrease in moose body condition and survival.     

Instar development and disengagement rate of engorged female winter ticks,Dermacentor albipictus (Acari: Ixodidae), following single- and trickle-exposure of moose (Alces alces)

Seven hand-reared moose (Alces alces) calves and one yearling were infested with 30 000 larvae each of the winter tick,Dermacentor albipictus, either by single- or trickle-exposure (1000/day). They were examined weekly for instar changes from September/October until late May. By 2 and 3 weeks post-exposure, most larvae on single- and trickle-infested moose, respectively, had fed and molted to nymphs. Thereafter, tick development was similar between both infestation techniques. Nymphs dominated the tick population from October to mid-February, and adults from mid-February to May. The peak of host disengagement by engorged females was late March in both years. Weights of engorged females from calf moose declined over time during the disengagement period.     

The diet of breeding female wolverines (Gulo gulo) in two areas of Finland

The wolverine (Gulo gulo) hunts and scavenges for food. We examined how the presence of a semi-domesticated reindeer (Rangifer tarandus tarandus) influences the diet of breeding female wolverines in Finland. We compared the dietary composition of wolverines breeding in the reindeer management area (northern Finland) with that of wolverines breeding outside this area (eastern Finland) by analyzing 421 scats collected from six active dens in northern Finland and four dens in eastern Finland during 2004–2006. The occurrence of food sources in the diet was assessed for both areas using logistic mixed-effects models. Diet breadth per study area was also calculated. As expected, semi-domesticated reindeer was the most important food source (66 %) in northern Finland. Mountain hares (Lepus timidus) were the second most important food item (16 %). Wolverines also utilized grouse (7 %), small rodents (6 %), and moose (Alces alces; 4 %) in their diet. In eastern Finland, the most utilized prey species was moose (55 %), while the diet also comprised mountain hares (13 %), domestic pigs (Sus scrofa; 13 %), grouse (11 %), and small rodents (2 %). The diet of wolverines in eastern Finland included more moose and less semi-domesticated reindeers and small rodents than in northern Finland. The niche breadth did not differ between the study areas. In eastern Finland, the diet of wolverines shifted to 55 % moose and 0 % semi-domesticated reindeer; compared to 4 % moose and 66 % semi-domesticated reindeer in northern Finland. Our study highlights the important role of ungulates in the diet of breeding female wolverines. In areas with a low density of medium-sized ungulates, scavenging for wolf- and human-killed moose and carcasses on feeding sites plays an essential role in food acquisition by wolverines.     

Ecology, nutrition, and timing of reproductive events in an Asian primate, the Hanuman langur (Presbytis entellus)

Ecological conditions, feeding and ranging behaviour as well as physical condition of female Hanuman langurs ( Presbytis entellus ) were studied in order to analyse the major influences on the timing of reproductive events. The langurs inhabited a semi-evergreen forest dominated by Sal trees ( Skorea robusta ). The climate was dominated by the summer monsoon lasting from May to September. Availability of plant phytophases was markedly seasonal, with fruiting as well as flushing of the six main food plants during the monsoon. Feeding and ranging behaviour of the females varied with food availability and its distribution. High dietary quality was only obtained during a short period from May to July. Physical condition of the females varied in accordance with dietary quality and energy expenditure, with a good physical condition during the second half of the year. Births occurred from January until June, with most births around the energetically worst period of the year. The results indicate that, in contrast to several other non-human primates, most females of this population gave birth too early to meet the optimum lactation requirements. Complete weaning mainly took place during an energetically bad time of the year (October to December). However, it can be inferred that the reduction of suckling bouts prior to the next conception took place when high quality food was available. Conceptions were confined to the months of July to November, coinciding with the time of best physical condition. Moreover, females who conceived were in a better physical condition than those who failed to conceive, suggesting a primary influence of nutrition on the probability of conception. Seasonality and timing of births may be the result of a regular seasonal shortfall of resources influencing the ability of the females to ovulate and to conceive.     

The influence of prey consumption and demographic stochasticity on population growth rate of Isle Royale wolves Canis lupus

The relationship between the rates of prey capture and predator population growth is a fundamental aspect of predation, yet it is rarely measured for vertebrate predators. For the isolated wolf population on Isle Royale, annual variation in kill rate explains 22% of the variation in wolf population growth rate. From the slope of this relationship, we estimate that the production efficiency (ratio of production to respiration) of wolves is between 0.5% and 1.5%. More generally, we assess the relative extent to which wolf population growth rate is affected by density dependence, prey availability (moose, Alces alces ), winter weather, and demographic stochasticity. Prey availability explains the most variation in wolf growth rate (42%), but this is only recognized after accounting for the influence of a disease-induced population crash and age structure of the prey population (i.e. number of vulnerable moose, >9 years of age). Demographic stochasticity accounts for approximately 30% of the variation in wolf growth rate. This recognition is important, but not surprising, given that the average population size of Isle Royale wolves is 22. Previous work indicates that the effect of winter climate, as mediated through prey vulnerability and kill rates, is substantial. This work indicates that the direct effect of winter climate is weak, and explains only about 4% of the variation in wolf growth rate (P=0.10).     

Ecological correlates of a tick-borne disease, Anaplasma phagocytophilum, in moose in southern Norway

As the distribution and abundance of ticks increase, so do the risks of tick-borne diseases. Anaplasma phagocytophilum, transmitted by Ixodes spp. ticks, is a widespread tick-borne infection causing tick-borne fever (TBF) in domestic ruminants and human granulocytic anaplasmosis. However, the role of wildlife in its epidemiology is poorly understood. Evidence of infection has been detected in wild cervids, but the pathogenicity and ecological consequences are unknown. We conducted a serological study of moose (Alces alces) in two populations in southern Norway, one where TBF was endemic (Telemark) and the other where sheep ticks (Ixodes ricinus) were essentially absent (Hedmark). Seroprevalence to A. phagocytophilum antibodies was 79 and 0 %, respectively. In Telemark, seroprevalence was significantly higher among females that calved successfully (85 %) than among others (50 %). Body mass and winter mass change were unrelated to serostatus. Relative abundance of questing ticks in Telemark was highest in deciduous forest and lowest in mature coniferous forest and higher at easterly aspects and altitudes below 350 m. Habitat factors associated with high tick abundance were risk factors for seropositivity among moose. Our findings were consistent with anaplasmosis causing a persistent subclinical infection in moose without population-level effects. Further work is needed to establish the importance of moose as a reservoir for the disease in sympatric domestic livestock.     

Impact of climate change and prey abundance on nesting success of a top predator, the goshawk

Contemporary research has documented a large number of shifts in spring phenology and changes in distribution range although the average spring temperatures have increased by only 0.3–0.6 °C over the past 100 years. Generally, earlier breeding birds have larger clutch sizes, and the advancing spring could thus potentially increase breeding success. Shifts in spring phenology can, however, be crucial for bird reproduction, and mistiming the breeding event may even have negative consequences for population development. Our aim was to explore how weather and prey abundance relates to the breeding performance of a north European top predator, the northern goshawk Accipiter gentilis. Our nationwide dataset from Finland, spanning the period 1989–2004, shows that ambient weather has a greater impact on the timing and success of breeding than the density of grouse Tetraonidae, the main prey of goshawks. Higher early spring temperatures were associated with advancing hatching date of goshawks. Correspondingly, grouse density and temperature during laying and brooding were positively associated with brood size, while precipitation showed a negative connection. Applying our models to a future scenario of climate warming, combined with a 50 % reduction in grouse density, suggests that average breeding dates will advance only 2.5 days and average breeding success would remain the same. Notably, breeding success was not spatially equal throughout Finland, as northern and eastern populations suffered most from declining grouse densities. The observed pattern is thus the opposite to what is expected from a population situated at the northern edge of its distribution range, and thus may help to understand why populations may not increase at the northern edge of their thermal distribution due to climate change.     

Population dynamics, growth and reproduction of Corophium insidiosum (Crustacea: Amphipoda) at low salinities in Monolimni lagoon (Evros Delta, North Aegean Sea)

Distribution, population dynamics, growth and aspects of reproductive biology of Corophium insidiosum were investigated in Monolimni lagoon. Samples were collected in July 1997 (at 30 psu S) and during February 1998–May 1999 (at 0.1–5.7 psu S). Corophium insidiosumwas almost exclusively found in the outer part of the lagoon, which showed a higher water renewal rate. Population density gradually decreased during winter and spring, when salinity was lower than 1 psu and the amphipod finally vanished from the lagoon. Salinity increase during summer (1.2–5.7 psu) was followed by the re-occurrence of C. insidiosum with a time lag of 2–3 months. Population density increased in autumn and peaked in early winter at salinities 1.6–4.2 psu. Three cohorts appeared in the population during September 1998–March 1999. Breeding activity peaked in early autumn (14–21?°C, 4 psu S) and ceased after December (2–6.5?°C, ¡1.5 psu S). The preponderance of females in the large size classes resulted in a female- biased sex ratio in the whole population. The population showed a growth rate of 7.5–11.2 μm d^?1 being faster in autumn (9–21?°C, 3–4 psu S) than in winter (2–12?°C, 0.2–3 psu). An exponential relation existed between body length and cephalic length or dry body weight, while brood size was directly related to body length. Mean brood size was small (4.96 early embryos) and egg loss during development high (53%), possibly as a consequence of low salinities.     

A noninvasive and integrative approach for improving density and abundance estimates of moose

Acquiring demographic data for moose (Alces alces) can be difficult because they are solitary in nature, they prefer densely vegetated and mountainous habitats, and they often occur at low density. Such data, however, are essential for long-term population monitoring, evaluating management practices, and effective conservation. Winter aerial surveys are the standard method for estimating moose population parameters, but they can be logistically challenging, expensive, and subject to sightability correction, which necessitates the capture of study animals for initial model development. Herein, we demonstrate a noninvasive alternative approach for estimating population parameters of moose in northern Yellowstone National Park, where aerial surveys were attempted but proved ineffective. We determined individual moose genotype and sex using microsatellite polymerase chain reaction amplification of DNA extracted from fecal pellets, integrated ancillary pellet sample data (i.e., metadata) in genotype analysis to aid in the identification of matching genotypes, and used spatially explicit capture-recapture (SECR) modeling to estimate sex-specific density and abundance. We collected 616 samples over 3 consecutive winters (Dec 2013–Apr 2016) and within 2 sampling occasions each winter. We recorded 514 captures of 142 individual moose (69 males, 73 females). Overall density ranged between 0.062 moose/km² and 0.076 moose/km² and averaged 0.034/km² for females and 0.033/km² for males. Abundance estimates were 150 moose in 2013 (female = 76, 95% CI = 55–105; male = 74, 95% CI = 54–103), 186 in 2014 (female = 95, 95% CI = 63–142; male = 91, 95% CI = 60–138), and 160 in 2015 (female = 79, 95% CI = 58–108; male = 81, 95% CI = 59–110). Average population sex ratio was 0.99 males/female. We demonstrate that SECR analysis of fecal DNA genotypes, using metadata in genotype analysis to help identify matching moose genotypes, is a promising alternative method for estimating sex-specific density and abundance of a low-density moose population in a mountainous and forested landscape.     

Climate effects on nesting phenology in Nebraska turtles

A frequent response of organisms to climate change is altering the timing of reproduction, and advancement of reproductive timing has been a common reaction to warming temperatures in temperate regions. We tested whether this pattern applied to two common North American turtle species over the past three decades in Nebraska, USA. The timing of nesting (either first date or average date) of the Common Snapping Turtle (Chelydra serpentina) was negatively correlated with mean December maximum temperatures of the preceding year and mean May minimum and maximum temperatures in the nesting year and positively correlated with precipitation in July of the previous year. Increased temperatures during the late winter and spring likely permit earlier emergence from hibernation, increased metabolic rates and feeding opportunities, and accelerated vitellogenesis, ovulation, and egg shelling, all of which could drive earlier nesting. However, for the Painted Turtle (Chrysemys picta), the timing of nesting was positively correlated with mean minimum temperatures in September, October, December of the previous year, February of the nesting year, and April precipitation. These results suggest warmer fall, and winter temperature may impose an increased metabolic cost to painted turtles that impedes fall vitellogenesis, and April rains may slow the completion of vitellogenesis through decreased basking opportunities. For both species, nest deposition was highly correlated with body size, and larger females nested earlier in the season. Although average annual ambient temperatures have increased over the last four decades of our overall fieldwork at our study site, spring temperatures have not yet increased, and hence, nesting phenology has not advanced at our site for Chelydra. While Chrysemys exhibited a weak trend toward later nesting, this response was likely due to increased recruitment of smaller females into the population due to nest protection and predator control (Procyon lotor) in the early 2000s. Should climate change result in an increase in spring temperatures, nesting phenology would presumably respond accordingly, conditional on body size variation within these populations.